The principal goal of this project is to elucidate function of the sodium pump, in particular we are interested in the transient kinetics of the sodium pump. A collaboration with J. Froehlich of NIA is directed at determining the extent to which oligomeric interactions of the sodium pump contribute to the efficiency of cation transport. We have obtained evidence, by a variety of techniques, that "out-of-phase" interactions of two or more alpha subunits occur in the native state of this and other P-type cation pumps.